import java.util.Scanner;
public class Exam1 
{
	public static void main(String[] args) 
	{
		float x, aver,sum,n=0;
		Scanner reader=new Scanner(System.in);
		sum=0;n=0;
		x=reader.nextFloat();
		while (x!=0)
		{ sum=sum+x;
		  x=reader.nextFloat();
		  n=n+1;
		}
		aver=sum/n;
		System.out.println("average="+aver);
		
		
	}
}